Interestingly, the loss of ice from the Northeast Greenland Ice Stream (NEGIS) took place not only during the warm Holocene period, but also during a period thought to be very cold preceding the last glacial maximum, the researchers say.

The findings suggest that NEGIS is particularly sensitive to environmental changes, which may exacerbate the influence of anthropogenic climate change. Results of the study are being published today in Nature Communications.

Parts - Ice - Sheet - Others - Evidence

"There are some parts of the ice sheet that are relatively stable and others that show evidence of very rapid retreating -- a pattern we're seeing today as well as thousands of years ago," said Anders Carlson, an Oregon State University geologist and co-author on the study. "Some of it relates to bed topography -- when the bed is below sea level, it stabilizes that part of the ice sheet. In low spots, it is unstable."

Carlson said different factors may help explain the ice mass loss, including orbital forcing and warm summer temperatures. The path of the Earth's orbit put it closer to the sun some 9,000 years ago, breaking the planet out of its glacial maximum. NEGIS showed significant ice loss.

Loss - Ice - Period - Maximum - Years

Yet it also showed a loss of ice during the period preceding that maximum, about 41,000 to 26,000 years ago, which is thought to have been very cold. OSU paleoclimatologist Christo Buizert, also a co-author on the study, reconstructed air temperatures from that period using ice core analysis and found that air temperatures indeed were much colder than average,...